Neurosonology.

Transcranial Doppler (TCD) is called the "doctor's stethoscope for the brain," and the use of TCD with portable carotid and vertebral duplex scanning provides structural and physiologic imaging extension of the neurologic examination. Ultrasound expands the ability of clinicians to detect, localize, and quantify disease and to evaluate hemodynamic responses, thus providing tools for a neurovascular examination at bedside.